X90 mobile modules
X90 mobile system User's manual V 1.20 - Translation of the original manual
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5.2.1.8 Derating
MF-PWM output
These outputs are implemented as push-pull or "active clamp" outputs. The advantage of these drivers is the
reduced power dissipation when switching inductive loads.
Only consecutive outputs can be configured for parallel operation (e.g. 2, 3, 4). When used as an input, the driver
is switched to a high resistance level (default).
Due to the additional dead time losses with outputs connected in parallel (with inductive loads), a derating of max.
PWM frequency = 1500 / maximum current per output must be observed for the PWM frequency:
Example 1:
Parallel connection of 2 outputs with inductive load 6 A:
Load per channel 6 A / 2 = 3 A
Permissible switching frequency: 1500 / 3 A = 500 Hz
Example 2:
Parallel connection of 2 outputs with inductive load and utilization of the 4 A nominal current per channel.
Maximum current: 2 x 4 A = 8 A Maximum frequency: 1500 / 4 A = 375 Hz
5.2.1.9 Melting integral i
2
t
The output is designed for a temporary overload (see table) for a period of 2 seconds. If more current is needed
for a certain time, less current must flow during the remaining time in order to maintain the melting integral.
1)
Let-through current
Multifunction outputs
79.4 A
2
s
MF-PWM 6 A
35.3 A
2
s
MF-PWM 4 A
40.5 A
2
s
MF-DO
Calculating the remaining-time current
Example
A boost current of 8 A is needed for a duration of 0.5 seconds.
1)
If a current of >10 A (MF-PWM) or >20 A (MF-DO) flows, 25 A is calculated.
